carburetor choice

[jopizz]

There was a thread a while back about the secondarys sticking that I remember. It works by vacuum so unless the engine is running at high speed it's hard to replicate. I think the problem was fixed by changing the carb gasket. I believe he was using a gasket that didn't have the four complete holes. After changing the gasket to one with the holes it seemed to work. At least that's what I remember.

John

[davidmij]

John, once again you nailed it. I cleaned it up, adjusted things according to the manual and went for a spin. It still got stuck at high idle after I step on the secondarys. I pull over, push the secondary throttle closing lever down, and it idles normal.

So I did it again, step on it till the secondarys kick in, it's at high idle, but this time I shut the engine off, and it drops down on its own. Hence, the secondary vacuum is the issue. The gasket looks good, but it is the kind without the compete holes. I'll try replacing it and see what happens.

thx Dave J

[KULTULZ]

The secondary throttle blades hanging on an incorrect base mounting gasket is common as today's kits are not as quality as they once were. The blades may also be hanging due to corrosion/residue buildup. You mentioned you have an open base gasket? It needs to be the four holer as the vacuum signal(s) will be interrupted without.

Also, there is a tiny set screw to adjust the secondary's closing. Also, the secondary diaphragm (not included in kit) may be broken or the linkage binding.

The original FORD kit was PN C2SZ 9A589-D. These were available just a few years ago. It is a QUALITY KIT.

Also, FORD had trouble in the early years with the metal secondary operating arm. A re-design went to white nylon. Make sure this upgrade has been done also.

[Yadkin]

Mike's carb parts has a basic rebuild kit for $30. You need to order the secondary diaphragm separately; it's either $10 or $30 depending on the male or female linkage, and you can't tell until you pull the cover off. They also sell a "complete" hardware kit for I think $60, includes the secondary diaphragm, floats, screws (but no lockwashers) and other stuff. The base gasket on the basic kit is wrong for most cars, but you can order the correct one from Advance for around $2.

So all parts including shipping will run you between $50-$100. It's hard to say if $250 from a local mechanic is a "good deal" because who knows what's actually being quoted.

That being said, my advice to the OP is not to fear rebuilding a carb. It's an easy job, will take a Saturday afternoon for a first timer and someone with experience can do it in less than an hour. Clear a nice spot on your workbench or folding table, take your time and disassemble carefully while paying attention to the diagram and instructions given with the kit. Clean the soft pot metal and brass parts with carb cleaner, wood or plastic dental picks, Q-tips, and some fine steel wool. Wear nitril gloves. I'd also suggest buying a good set of hollow ground screwdrivers (online for about $30 plus shipping) as they are much less likely to "cam out" when loosening old screws. There are certain adjustments that need to be made while rebuilding and then while on the car and after an ignition tune. These are all things that you should learn to do by yourself, as old car mechanics are few and far, and no one can tune a car better than its driver.

[KULTULZ]

Good advice above-

http://www.mustangmonthly.com/howto/mump_1201_autolite_carburetor_rebuild/

[jopizz]

The GP-Sorensen kit that Autozone sells comes with the secondary diaphragm and the nylon shaft. Part # 96-134D. It's $24.99. It doesn't come with the completely closed gasket though.

John

[Yadkin]

I found the receipt for my hollow ground screwdriver set. Sold through Amazon, search "Grace USA Original Gun Care Screwdriver Set", for $38.50 plus shipping. Well worth the investment to protect the hundreds of slotted screws not just on the carb but all over the interiors of these cars. Not to mention your guns.

[davidmij]

I've done everything from pounding nails, to running a 6 foot (chuck diameter) lath, to painting cars, to assembly line work at GE, and now being a computer systems administrator, yet I never learned what a "hollow ground screwdriver" was. I've used them and knew how they worked, but I didn't know they had a name,,,,son of a gun.

Anyway, I rebuilt a couple of carbs when I was a kid, maybe now it's time I actually learned what is doing what. I had a carb kit from my other motor, the "GP Sorenson" $17.99 at Autozone. It had the diaphragm but I didn't use it because the old one was fine. So last night I used it to replace mine but it didn't help. It was an SOB getting the little press fit pin out of the old one because the one in the kit just had the hole.

I find it weird that the secondary throttle closing lever goes back to rest on the set screw when I shut it off and the vacuum drops, but while it's running it still sits about a 16th of an inch off the set screw (after they have kicked in) while running.

These Mike's videos; http://www.youtube.com/watch?v=SntO1M_7M-8
are really good. This one is my carb however mine doesn't have a "dashpot" whatever that does. I'll mess with it this weekend again. Tomorrow I'm headed all over the place to get stuff. Found a 9 inch third member in Albuquerque with 3.89 gears. The guy want $250 plus my 3.10 unit for it, and it's not even rebuilt. Seems pretty high to me but i can't find anything else in the state.
Also need a couple of rear brake cylinders, glass packs for the FPA headers that will be arriving tomorrow. YES! Gotta pick up my air compressor, a garbage disposal for a rental house, paint, etc. Now if i just had more time to build all this stuff!

thx for all the good advice, Dave J

[Yadkin]

All the dashpot does is keep the throttle from closing quickly. This prevents stalling in certain cases.

I just replaced mine and the new one has a much longer "point" (for lack of an actual name) on it so I called the vendor. He said that's the only one they carry so most guys cut it down.

[KULTULZ]

I find it weird that the secondary throttle closing lever goes back to rest on the set screw when I shut it off and the vacuum drops, but while it's running it still sits about a 16th of an inch off the set screw (after they have kicked in) while running.

...mine doesn't have a "dashpot" whatever that does. I'll mess with it this weekend again.

There is a lever on the right side of the primary throttle shaft that will (or should) contact and completely close the secondary shaft throttle plates (to adjustment) once the accelerator is fully released. Your problem lies there somewhere. The secondary throttle plates are hanging open slightly causing a un-metered vacuum leak, hence an enhanced idle speed.

The dash-pot is used on AT cars only. It prevents engine stall from the AT convertor drag from stalling the engine either while slowing abruptly or coming to a stop.

http://www.carbkitsource.com/carbs/tech/Ford/4100-index.html

[davidmij]

Thanks Gary! I saw that when I was trying to adjust the fast idle cam. My manual calls it the fast idle lever. Mine is a screw with the head filed down so the fast idle adjusting screw will clear it. I'm pretty sure it not the correct pin being that someone put a filed down screw in there. I had thought that if it were fatter it would seat the secondarys like it should. Here's the picture from the manual with an arrow pointing to where mine has the screw.
Any idea on where to order a new one? Or any carb parts and pieces for that matter?

thx a ton, Dave

[KULTULZ]

In addition to the URL in my above post- http://www.carbkitsource.com/carbs/kits/CK014BHW.htm

The fast idle lever also prevents the secondaries from opening with the choke not fully opened.

Do you have a Shop Manual showing the 4100? If not, they also offer the Shop Manual pages as a reference.

[jopizz]

The original pin was plastic which is why they don't last very long. I usually just use a cut down nail. As long as it just fits through the hole it should be the right width. The idle screw will keep it in place. It's not a real high tech system. You didn't mention if you changed the gasket.

John

[KULTULZ]

For your info Ford has different carburetor jets listed for 5000-10000 ft. I'm not sure whether they are installed at the factory or by the dealers.

John

Correct. When you go to the MPC Parts List for your particular carburetor (identified by Carb Asm Tag I.D. No.) the jets (Basic Service PN 9533) will be shown by your altitude if it pertains to your particular situation.

[davidmij]

Yes, my manual does show it, it calls it a "Ford 4 barrel". The screw that is in there is a tad small for the hole and rattles around so I'll find a nail or proper sized pin of some sort.

The fast idle lever is preventing the secondaries from kicking in. In other words it is working correctly.

I did not change the gasket, but the mechanism moves very freely and is very clean. It doesn't bind anywhere at all. The only time it sits high is when the motor is hot and running, and after the secondaries have kicked in due to me flooring it.

My carb tag says it's a Fomoco "C5AF F" below that it has
"C 5DB". Do you know if that number tells me anything about the altitude?

I'm off to Santa Fe now to run some errands. If I get back in time I'll try fixing and ordering some of the items you guys suggested.

thanks a ton!